Synthesis of a castor oil-based quaternary ammonium surfactant and its application in the modification of attapulgite

Castor oil-based quaternary ammonium surfactant (COQA) was synthesized by an ester-exchange reaction of refined castor oil (CO) (raw material) with N,N-dimethyl ethanol amine followed by quaternization with epichlorohydrin (ECH). Its surface activity and structural features were determined. The critical micelle concentration (CMC) of the surfactant at 25 °C was 1.79 × 10−3 mol/L. The surface tension of an aqueous COQA solution at CMC was 38.19 mN/m. Subsequently, the synthesized COQA was used to modify attapulgite (ATP) by binding it to the surface of ATP. The change in the morphology of the modified-ATP (M-ATP) was attributed to the presence of the COQA bound to the surface of the rod-shaped crystals, although the crystal structure of the silicate did not change. Compared to ATP, the microstructure of the M-ATP was less rigid